We have a home-built interior similar to / based on the 50 layout. With the rear seat in the upright (ie, 'seat') position, we use the rear space like a crib area and our toddler sleeps back there. She was about 18 months old for her first trip, but that is just a function of how long we've had the van together - I think she would have been fine back there at a younger age too. We use therma-rest's vertically to form a perimeter that is padded and insulated.

This also gives you a confined space that is fairly easy to shade or darken as needed. I don't think I have any photos, but hopefully that gives you an idea.

Though it is hard to store, we used to just take the pack-and-play along, if you have one. My kids got familiar with it as "their space" and would always sleep or hang there when we were camping or staying anywhere away from home. I had several campers during the time we were using it and I would just set it up on top of a bed (like on your sofa bed in the back of the 50 plan). We used ours in a pop-up by just folding the mattress out of the way and sitting it on the bare wood below so it was rock solid. The sides come up to the ceiling but we were always able to make it fit, and they weren't going anywhere.

Thanks for the ideas. I have a plan developing (in my head) that involves a pack and play, a piece of plywood with holes drilled out to fit the feet of the pack and play and some old legs off a folding card table. Stay tuned.

I'm looking forward in seeing what you come up with. I to am trying to figure out the best arrangement for my 16 month old. I saw etbadger's post of where he put a travel pen up on the penthouse bed and put a zipper one side of it to get his daughter in and out easily. I'm liking that idea.

I will 2nd the Pack and Play behind the rear seat on a RB-50 layout. Don't think there is much need for additional work or over thinking, just put the pack and play on the floor. You can dark out that area pretty well and easy access from the back door or over the seat. Being behind the rear seat makes it almost a separate room for them so you can still enter/exit the front without too many problems. It has worked well on 6 trips so far.

I highly recommend, very ingenious design, very difficult for a toddler to climb out of, very light and fantastic space economy both folded and set-up. I forget the cost, probably not cheap but saved us a bunch of times both in the SMB and internationally.

We would pull down the back half of the penthouse bed and bungie the pea pod in place up there while we slept on the goucho below. We rigged up a blanket that would drop from the ceiling down in front of the pea pod to keep it dark so that we could keep some lights on in the van.

Once she got bigger we just changed positions with her. We put her behind the the rear seat (with the goucho folded up) and we slept in the penthouse. We again rigged up a blanket to block off light from the rest of the van.

She has gotten too big for the pea pod, so we have ditched it and let her sleep behind the rear seat. We've been worried about our dog trying to snuggle with her during the night and creating chaos, but keeping the blanket blocking her space from the dog's spot on the rear seat has worked well.

I should add that the pea pod folds down onto itself and is thin enough that we can slide it in cabinet right next to the porta potty. It's worked great.

I'm looking forward in seeing what you come up with. I to am trying to figure out the best arrangement for my 16 month old. I saw etbadger's post of where he put a travel pen up on the penthouse bed and put a zipper one side of it to get his daughter in and out easily. I'm liking that idea.

Now that we have two kiddos, we switched to two of the above mentioned pea-pod tents. They think it is great to have their own 'personal' space, and we throw a blanket over to cut down on light and keep them a bit warmer when it gets cold. At about 2.5yrs they are capable of opening the zipper themselves, so now they entertain themselves by doing body-slams on each other through the tents when least-expected.

We did put up a reinforced fabric wall at the front of the penthouse bed to cut down on light heading up, and keep them from falling off the edge when wrestling. It clips to the bed front and the roof ceiling in a number of places with 1" nylon webbing.